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Marh s, 1,932. F. FILLER. JR" 1,848,802

' PROCESS or: magma M'ULIIC'O'LOR COPYIVNG SCREENS Filed May 16. 1950 Patented Mar. 8, 1932 UNITED STATES PATENT OFFICE FRANZ FILLER, 33., OF MUNICH, GERMANY PROCESS FOR MAKING MULTICOLOB COPYING SCREEIIS Application filed Kay 16, 1980, Serial No.

10 lows that a perfect positive picture can only be produced if the distorted elements of the negative are contained in the same degree of distortion in the copying screen, in order to make a correct correspondence of the individual screen elements possible.

The present invention refers to a process for making polychromatic copying screens, in which a correct correspondence of the copying screen with the distorted negative is made possible by very simple means; in other 'words, the exact degree of distortion. in the negative is reproduced in the copying screen. The process vis adapted only for copying screens made up of uniform or regular ele- 25 ments, as, for instance, line screens, dot screens, check pattern screens.

In the accompanying drawings the individual phases of the process are shown with the help of the parts used in the process; for the sake of distinctness these parts and especially the individual screen elements are much enhgged and their distortion much exaggera Fig. 1 shows the exposure of a photographic plate through a standard polychromatic screen using divergent light of a single color. 4

Fig. through the finished plate from Fig. 1, parallel rays of light being used.

Fig. '3 illustrates the printing of a new screen using the. clich or printing block from Fig. 2. r

ccording 'to the new process, a sensitive layer on atransparent base 8, for instance, a

} glass plate, is exposed behind a standard, for instance, engraved, polychromatic screen 1* with the help of the lens '0. Exposure is.

made in such manner, that of the several col;

2 ors contained in the screen r, onecolor only,

2 shows the exposure of a clich 452,862, and in Germany May 25, 1929.

for instance, blue, is reproduced on the base 8, which is attained by means of an exposure with blue'light. The screen 1' in front of the sensitive layer causes distortion, the degree of distortion depending on the focal length of the lens 0; this distortion is clearly shown in Fig. 1, and consists for instance in a gradual widening of the intervals between the individual screen elements towards the edges of the plate or sensitive layer.

With thehelpof this distorted image on the plate 8, a clich or printing block, forinstance, a zinc clich his made, the distorted image being transferred from the plate to the clich in known manner by chemical action with the help of parallel light rays, as

shown in Fig. 2. This printing block k is now used to print the polychromatic copying screen p in such manner, that first only one color (blue) is printed, the distortion in the copying screen then obviously exactly corresponding with the distortion in the negative is. Hereupon the printing block k is displaced the distance of one color division, that is, the distance of one screen element from v the next, this being, for instance, a red element, and the printing is then repeated, this time with red color; this process of displacing the block and printing is repeated until all c0l0rs.are printed on the copying screen, the block being each time freshly inked with the appertaining color. In most cases the three colors blue, red and green will be found suflicient.

What I claim is: a

1. The Ste 5 in the process of making 'a polychromatlc color screen corrected for light distortionefi'ects which consist in passing divergent rays of monochromatic light through a standard polychromatic screen and causing 90 them to immediately impinge on a sensitized photographic film whereby to produce a distorted image of said screen, utilizing the film as a negative and printing therethrough with parallel rays of light on a block having a sensitive photographic surface. treating the blockto form a printing block, and printing from said block in monochrome on screen material to form the corrected screen.

2. The steps in the process of making a 1M polychromatic color screen corrected for light distortion efiects which consist in passing vergent ra s of monochromatic lig t through a standar polychromatic screen and cans- 5 ing them to immediately impinge on a sensitized photographic film whereby to roduce a distorted image of said screen, uti ing the film as a negative and printing therethrough with parallel rays of light on a block having a sensitized photographic surface, treating the block to form a printing block, and rinting from said block on screen materlal in successive monochrome colors with each successive color displaced on the screen material ,15 with respect to the precedin color.

In testimony whereof I a my signature.

FRANZ FILLER, JUNIOR. 

